VNAV Weak Performance

[EgyptianAviator 0]

Hey guys,

 

I've had the 777 for over 4 months now and I've had the hang of it quite well now. As most of us, I downloaded the SP1. However since then, my aircraft's VNAV had been acting quite strange, The climbs are very weak and I can't get past the 1000 FPM climb if I'm to avoid stalling.what I think happed is that when I derate my takeoff using an assumed temp. it derates all the performance not only the takeoff. For instance I'm currently flying a flight with 60% payload =ZFW 414 and 45,000 Lbs of fuel. I've had an assumed temp (On the Thrust Lim page) of 55 degrees which derated the thrust to around 93% which is more than plentiful for takeoff, but won't allow me to climb later on. Does anyone know how to resolve the climb issue? Moreover, when cruising at FL190 (Such as the current flight) The autothrottle keeps the throttles always at more than 100% to keep a speed of Mach .865. I'm definite there's something I'm doing it wrong. I just don't know what.

 

Thank You,

Mohammed El-Dakamawy

[markjj 47]

What is the outside temperature during these flights. It almost sounds as if the weather was too hot causing a decreased aircraft performance.

[markadeane 272]

Mohammed,

 

As MarkJJ has suggested this sounds like an air temperature issue. Are you using a real weather add-on? If you see a positive air temperature reading on the display as you climb up, and it keeps increasing rather than decreasing, then the weather add-on is the problem. Try a flight without the real weather add-on and see if the same problem occurs.

 

For what it's worth, I use Active Sky Next and I do not encounter the temeprature issue, but I occasionally used to with previous versions of Activesky.

[EgyptianAviator 0]

What is the outside temperature during these flights. It almost sounds as if the weather was too hot causing a decreased aircraft performance.

This current flight, the temp was 32 degrees at the dept. airport.

Which I think is only 2 degrees more than the flat rated at 30C

Mohammed,

 

As MarkJJ has suggested this sounds like an air temperature issue. Are you using a real weather add-on? If you see a positive air temperature reading on the display as you climb up, and it keeps increasing rather than decreasing, then the weather add-on is the problem. Try a flight without the real weather add-on and see if the same problem occurs.

 

For what it's worth, I use Active Sky Next and I do not encounter the temeprature issue, but I occasionally used to with previous versions of Activesky.

Mark,

I'm afraid I don't use any weather software, only vatsim. And the temp is decreasing as I climb as well. Active sky will be out of the question for me to but currently as I'm running on a USB Dongle for internet xD

[Tabs 2,790]

Try deleting your FSX\Modules\FSUIPC4.ini file and let it build a new one. There's a corruption that can happen that screws up the thrust axis and causes symptoms like what you're describing.

[ddswh1pk0s 8]

If you're using FSinn there's a well known issue of the aircraft not being able to climb because the temperature remains too high

[RudiJG1 172]

If you're using FSinn there's a well known issue of the aircraft not being able to climb because the temperature remains too high

 

...if you have FSInn's weather enabled, it injects too high a temperature at high altitudes, thus affecting jet engine performance. Turn FSInn weather OFF.

[EgyptianAviator 0]

Try deleting your FSX\Modules\FSUIPC4.ini file and let it build a new one. There's a corruption that can happen that screws up the thrust axis and causes symptoms like what you're describing.

Tried that as well, with no outcome as well. But thanks for the assist Ryan

 

If you're using FSinn there's a well known issue of the aircraft not being able to climb because the temperature remains too high

...if you have FSInn's weather enabled, it injects too high a temperature at high altitudes, thus affecting jet engine performance. Turn FSInn weather OFF.

THIS ACTUALLY IS THE ISSUE AND IT'S RESOLUTION

Thank you very much Antoni and Wayne.. You're both stars (Y) B)  :rolleyes: